Sidewinder Therapeutics closed a $137 million Series B financing to advance a pipeline of bispecific ADCs. The company plans to use the funding to progress SWT012 toward an Investigational New Drug filing with the FDA by the end of 2026 and to initiate clinical development in 2027, with additional programs targeting lung and colorectal cancers slated for development by 2027. Sidewinder said its antibodies are paired with Lonza’s Synaffix site-specific linker-payload system through a multi-target licensing agreement signed in January 2026. The investment also included co-leads Frazier Life Sciences and Novartis Venture Fund, with OrbiMed returning alongside new investors.